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Rolling Thin Wall Brass Tube

Joined
Jan 22, 2019
Hey All,
I'm not sure this thread belongs on this site, since it's not about machining, but I'll give it a shot:

I'm rolling some 2" O.D. x 0.050" wall brass tubing for a bar footrail and I'm having lots of trouble. It's kinking, obviously.

I'm using a JD Squared Model 32 tube and pipe bender with 2" dies that give the bend a 7.5" outside radius. My last try I sleeved the primary tube with 1.875" O.D. x 1/16" wall brass tube, capped one end, filled it with PACKED, moist sand, and capped the other end. Still, I'm getting large kinks along the inside of the roll.

Any advice?
Thanks,
Mat
 

Dumpster_diving

Cast Iron
Joined
May 18, 2017
Location
Massachusetts
Not an expert, so I'll defer to others that answer. But two observations:
- 7.5" outside radius seems like a pretty tight radius for 2" OD tubing. Are you sure that's even an achievable bend (and doesn't require a 90 degree ell fitting for bar-rail)?
- Not following why you're sleeving the primary tube with another tube inside of it. But the tightly packed sand seems like an appropriate step. Can you not contain the sand within the 2" primary tube and skip the inner tube?
 

Illinoyance

Stainless
Joined
Aug 24, 2015
The tubing is probably in a work hardened condition. Annealing would make it more workable. As Dumpster said that small a radius may not be possible. I doubt that annealing and using a bender with a mandrel would achieve that tight a radius.
 

Peter Colman

Stainless
Joined
Sep 22, 2004
Location
Rugeley UK
You could try filling the tube with low melting point metal, in theUK we call it Woods metal, I think it is based on Bismuth, it melts easily and can be run out after bending
 
Joined
Jan 22, 2019
You could try filling the tube with low melting point metal, in theUK we call it Woods metal, I think it is based on Bismuth, it melts easily and can be run out after bending

That's a cool idea. I've used that stuff a bit, but got scared when I realized it contained plenty of lead and cadmium.

As for the others: I was worried folks might say it's too tight of a radius. Annealing had crossed my mind so I may give that a shot.

Thanks everyone.
 

bosleyjr

Diamond
Joined
Sep 30, 2006
Location
SE PA, Philly
Is 0.050" wall brass tubing sufficiently strong for a footrail? Or is this the standard thickness. I would have expected pipe, as a footrail will have BUFFs (big ugly fat fellows) like me standing on it.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
I rolled 50" of 7/8" OD copper with thickness .045 using this contraption I made. I worked down to a 10" diameter using about 4 passes.
Each run through the roller was harder to push through as the center wheel is adjusted downward. If I had to do it again I would have used
a Map gas torch to soften the tubing on each pass. I used 1/4 circle forms with a round groove to press the copper from a slight oval to
circular again. The message here is that slow and gradual worked for me.

DSC_0743.jpg

Got the idea from this. I was ready to make one like it but decided it was not worth it for just one job.

tubebender.jpg

Result.
DSC_0999.JPG
 

LKeithR

Stainless
Joined
Sep 1, 2011
Location
Langley, B.C.
I would imagine you need a mandrel bender. The old Pines benders work well


I agree. I don't think there's much hope of bending 2" OD x .050" wall brass tubing without some support on the
inside. And even then you'll most likely have to anneal the tube at the points where the bends takes place. A
rotary draw bender is not the tool for this job...
 

Hardplates

Stainless
Joined
May 8, 2019
Location
What once was a free country
I rolled 50" of 7/8" OD copper with thickness .045 using this contraption I made. I worked down to a 10" diameter using about 4 passes.
Each run through the roller was harder to push through. If I had to do it again I would have used a Map gas torch to soften the tubing
on each pass.

View attachment 271690

Got the idea from this.

View attachment 271691

Result.
View attachment 271692

That would put you around a 5.5:1 diameter to CLR ratio. The OP is trying to achieve 3.25:1 That is a huge difference and I just don't see it happening without a mandrel
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
My last try I sleeved the primary tube with 1.875" O.D. x 1/16" wall brass tube, capped one end, filled it with PACKED, moist sand, and capped the other end. Still, I'm getting large kinks along the inside of the roll.

Any advice?

Since you tried sand, have you thought about water inside and freezing it? Sand and water were ideas that I thought too much work for a long length.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Is 0.050" wall brass tubing sufficiently strong for a footrail? Or is this the standard thickness. I would have expected pipe, as a footrail will have BUFFs (big ugly fat fellows) like me standing on it.

The inside can always be filled with something. Concrete would probably make it too heavy.
 

crossthread

Titanium
Joined
Aug 5, 2004
Location
Richmond,VA,USA
Not long ago I was asked to make some sharp bends in some brass tubing for a fellow at the boat yard for some vents. I do not have any bending equipment so I took it to a muffler shop. It was kinking terribly and I gave up on that idea. I ended up kerfing the pipe and after forming the bend I silver soldered the kerfs. This was not a decorative piece and you could see the kerfs but only slightly. With that tight a bend you might have to get inventive.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
That would put you around a 5.5:1 diameter to CLR ratio. The OP is trying to achieve 3.25:1 That is a huge difference and I just don't see it happening without a mandrel

You missed the words, "The message here is that slow and gradual worked for me."

Agree about using a mandrel for a single shot bend.
 

Hardplates

Stainless
Joined
May 8, 2019
Location
What once was a free country
You missed the words, "The message here is that slow and gradual worked for me."

Agree about using a mandrel for a single shot bend.

It doesn't matter how slow and gradual you go, I don't see a nice bend that tight being formed on thin wall tubing without a mandrel or hydroforming. I've bent boiler tubes with sand in them and caps welded on the ends, while it does make the tube maintain the same volume, it does not totally prevent it from ovaling in the bend area even on heavy wall tube.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
It doesn't matter how slow and gradual you go, I don't see a nice bend that tight being formed on thin wall tubing without a mandrel or hydroforming. I've bent boiler tubes with sand in them and caps welded on the ends, while it does make the tube maintain the same volume, it does not totally prevent it from ovaling in the bend area even on heavy wall tube.

Especially when amateur methods like packing with sand are used.
 

Hardplates

Stainless
Joined
May 8, 2019
Location
What once was a free country
Especially when amateur methods like packing with sand are used.

I would hardly call using sand an amateur method. Less than ideal yes, but so is anything short of mandrel bending in the OP's situation. I was simply following the repair procedures laid by Babcock & Willcox, but then again their Nation Board R Stamp number is only in the single digits, #3 IIRC.

If you can ever get your hands on some B&W procedures they are very interesting reading, over 100 years of trial, error and engineering. Sometimes a pain to work to as they have a procedure for everything except how to wipe your own ass while on break, but lots of good info and emergency repair techniques.
 

Dumpster_diving

Cast Iron
Joined
May 18, 2017
Location
Massachusetts
Just another (non-expert) suggestion. Along the lines of Crossthread's advise: Perhaps you can cope the tube at the location of the bend. Similar to multiple kerfs but really only removing a 90 degree section leaving a small tab connected on the outside of the bend. With the bend area removed, bend the tab so the coped sides meet and make a single silver-solder joint. Will result in a sharp outside corner but might look ok. Otherwise follow Crossthread's and do multiple kerfs for a smoother outside radius.
 

Newman109

Diamond
Joined
Sep 4, 2006
Location
Sacramento County, California, USA California
Hey All,
I'm not sure this thread belongs on this site, since it's not about machining, but I'll give it a shot:

I'm rolling some 2" O.D. x 0.050" wall brass tubing for a bar footrail and I'm having lots of trouble. It's kinking, obviously.

I'm using a JD Squared Model 32 tube and pipe bender with 2" dies that give the bend a 7.5" outside radius. My last try I sleeved the primary tube with 1.875" O.D. x 1/16" wall brass tube, capped one end, filled it with PACKED, moist sand, and capped the other end. Still, I'm getting large kinks along the inside of the roll.

Any advice?
Thanks,
Mat



I've bent tubing using the sand packing method. I was doing heavy-wall 7/8" steel tubing for a motor scooter project. The trick is that the sand must be packed very tightly. I capped one end of the tubing, filled the tube with sand and then capped the other end. The second cap had a screw built into it that, when screwed in, would put the sand under a strong pressure. The bends came out OK. I can't say that this would work with thin-wall brass, however. See the picture.

I do know that some musical instrument makers fill their brass tubes with water and freeze them before bending.
 

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